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T O P I C R E V I E W

Robert Pearlman

James Webb Space Telescope (JWST)

The James Webb Space Telescope (sometimes called JWST) is a large, infrared-optimized space telescope.

Webb will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. Webb will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System.

Webb's instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.

Webb will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. Both the mirror and sunshade won't fit onto the rocket fully open, so both will fold up and open once Webb is in outer space. Webb will reside in an orbit about 1.5 million km (1 million miles) from the Earth.

In summary, the Panel concluded that the JWST Project is in very good technical shape. There is no reason to question the technical integrity of the design or of the team's ability to deliver a quality product to orbit. The problems causing cost growth and schedule delays have been associated with budgeting and program management, not technical performance.

Bolden released the following statement in response.

NASA Administrator Bolden Statement On The Webb Telescope

NASA Administrator Charles Bolden made the following statement today on the release of an independent panel's review of the James Webb Space Telescope project:

"I appreciate the work done by the James Webb Space Telescope's (JWST) Independent Comprehensive Review Panel (ICRP), and want to thank Sen. Barbara Mikulski for initiating this review. The ICRP report makes clear that, while JWST technical performance has been consistent with the project plan, the cost performance and coordination have been lacking, and I agree with these findings.

"No one is more concerned about the situation we find ourselves in than I am, and that is why I am reorganizing the JWST Project at Headquarters and the Goddard Space Flight Center, and assigning a new senior manager at Headquarters to lead this important effort. The new JWST program director will have a staff of technical and cost personnel provided by the Science Mission Directorate and report to the NASA associate administrator. This will ensure more direct reporting to me and increase the project's visibility within the agency's management structure. Additionally, the Goddard Space Flight Center's project office has been reorganized to report directly to the center director. That office is undergoing personnel changes to specifically address the issues identified in the report.

"I am encouraged the ICRP verified our assessment that JWST is technically sound, and that the project continues to make progress and meet its milestones. However, I am disappointed we have not maintained the level of cost control we strive to achieve -- something the American taxpayer deserves in all of our projects.

"NASA is committed to finding a sustainable path forward for the program based on realistic cost and schedule assessments. I would like to express my appreciation to the ICRP's chair, John Casani, and the rest of the team for producing an objective, unbiased and comprehensive assessment."

SpaceAholic

Got Your Back:

Webb has a primary mirror six times larger than the one found on the Hubble Space Telescope. In order for a primary mirror 21 feet in diameter to travel into space, it has to be broken up into multiple segments — in this case, 18 of them.

But for the 18 to act as one primary mirror, they have to be adjusted while in orbit. How this task is achieved is the focus of this episode of Behind the Webb: Got Your Back.

The first six of 18 segments that will form NASA's James Webb Space Telescope's primary mirror for space observations will begin final round-the-clock cryogenic testing this week. These tests will confirm the mirrors will respond as expected to the extreme temperatures of space prior to integration into the telescope's permanent housing structure.

The X-ray and Cryogenic Facility at NASA's Marshall Space Flight Center in Huntsville, Ala. will provide the space-like environment to help engineers measure how well the telescope will image infrared sources once in orbit.

Credit: NASA/MSFC/David Higginbotham

Above: NASA engineer Ernie Wright looks on as the first six flight ready James Webb Space Telescope's primary mirror segments are prepped to begin final cryogenic testing at NASA's Marshall Space Flight Center in Huntsville, Ala.

Each mirror segment measures approximately 4.3 feet (1.3 meters) in diameter to form the 21.3 foot (6.5 meters), hexagonal telescope mirror assembly critical for infrared observations. Each of the 18 hexagonal-shaped mirror assemblies weighs approximately 88 pounds (40 kilograms). The mirrors are made of a light and strong metal called beryllium, and coated with a microscopically thin coat of gold to enabling the mirror to efficiently collect light.

"The six flight mirrors sitting ready for cryogenic acceptance tests have been carefully polished to their exact prescriptions," said Helen Cole, project manager for Webb activities at Marshall. "It's taken the entire mirror development team, including all the partners, over eight years of fabrication, polishing and cryogenic testing to get to this point."

During cryogenic testing, the mirrors are subjected to extreme temperatures dipping to minus 415 degrees Fahrenheit (-248C) in a 7,600 cubic-foot (approximately 215 cubic meter) helium-cooled vacuum chamber. This permits engineers to measure in extreme detail how the shape of the mirror changes as it cools. This simulates the actual processes each mirror will undergo as it changes shape over a range of operational temperatures in space.

"This final cryotest is expected to confirm the exacting processes that have resulted in flight mirrors manufactured to tolerances as tight as 20 nanometers, or less than one millionth of an inch," said Scott Texter, Webb Optical Telescope element manager at Northrop Grumman in Redondo Beach, Calif.

A second set of six mirror assemblies will arrive at Marshall in July to begin testing, and the final set of six will arrive during the fall.

The Webb Telescope is NASA's next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope designed, Webb will observe the most distant objects in the universe, provide images of the very first galaxies ever formed and help identify unexplored planets around distant stars. The telescope will orbit approximately one million miles from Earth.

"The Webb telescope continues to make good technological progress," said Rick Howard, JWST Program Director in Washington. "We’re currently developing a new baseline cost and schedule to ensure the success of the program."

The telescope is a combined project of NASA, the European Space Agency and the Canadian Space Agency. Northrop Grumman is the prime contractor under NASA's Goddard Space Flight Center in Greenbelt, Md. Ball Aerospace & Technologies Corp. in Boulder, Colo., is responsible for mirror development. L-3- Tinsley Laboratories Inc. in Richmond, Calif. is responsible for mirror grinding and polishing.

Prior to taking a new telescope into space, engineers must put the spacecraft and its instruments through a "spin cycle" test for durability to ensure they'll still work after experiencing the forces of a rocket launch. Finding out they don't work once they're in orbit is too late. The structure that houses the science instruments of the James Webb Space Telescope is undergoing that cycle of tests during the weeks of May 23 and 30 at NASA's Goddard Space Flight Center in Greenbelt, Md. This structure is called the Integrated Science Instrument Module, or ISIM.

The Webb telescope will experience significant shaking and gravitational forces when it is launched on the large Ariane V rocket. The ISIM structure will house the four main scientific instruments of the telescope.

During the testing process, as the ISIM structure is being spun and shaken, engineers take measurements to compare with their computer models. If there are discrepancies, the engineers hunt for the reasons so they can address them. The huge centrifuge will spin at speeds close to 11 rpm, exposing the ISIM structure to about 10 times the force of gravity.

Webb is the successor to the Hubble Space Telescope and will serve thousands of astronomers worldwide. Webb will study the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of planetary systems capable of supporting life on planets like Earth, to the evolution of our own Solar System. The Webb telescope is a joint mission of NASA, the European Space Agency and Canadian Space Agency.

Robert Pearlman

Editor's note:The U.S. House of Representatives has proposed canceling the James Webb Space Telescope as part of cuts to NASA's 2012 Fiscal Year budget.

To keep this topic focused on JWST development efforts (so long as the telescope remains funded), please direct discussion of the budget to this thread.

Robert Pearlman

NASA release

NASA's Webb Telescope Completes Mirror Coating Milestone

NASA's James Webb Space Telescope has reached a major milestone in its development. The mirrors that will fly aboard the telescope have completed the coating process at Quantum Coating Inc. in Moorestown, N.J.

The telescope's mirrors have been coated with a microscopically thin layer of gold, selected for its ability to properly reflect infrared light from the mirrors into the observatory's science instruments. The coating allows the Webb telescope's "infrared eyes" to observe extremely faint objects in infrared light. Webb's mission is to observe the most distant objects in the universe.

"Finishing all mirror coatings on schedule is another major success story for the Webb telescope mirrors," said Lee Feinberg, NASA Optical Telescope Element manager for the Webb telescope at the agency's Goddard Space Flight Center in Greenbelt, Md. "These coatings easily meet their specifications, ensuring even more scientific discovery potential for the Webb telescope."

Credit: NASA/Chris Gunn

Above: The first six flight ready James Webb Space Telescope's primary mirror segments are prepped to begin final cryogenic testing at NASA's Marshall Space Flight Center in Huntsville, Ala.

The Webb telescope has 21 mirrors, with 18 mirror segments working together as one large 21.3-foot (6.5-meter) primary mirror. The mirror segments are made of beryllium, which was selected for its stiffness, light weight and stability at cryogenic temperatures. Bare beryllium is not very reflective of near-infrared light, so each mirror is coated with about 0.12 ounce of gold.

The last full size (4.9-foot /1.5-meter) hexagonal beryllium primary mirror segment that will fly aboard the observatory recently was coated, completing this stage of mirror production.

The Webb telescope is the world's next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope ever built, the Webb telescope will provide images of the first galaxies ever formed, and explore planets around distant stars. It is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

Mirror manufacturing began eight years ago with blanks made out of beryllium, an extremely hard metal that holds its shape in the extreme cold of space where the telescope will orbit. Mirror coating began in June 2010. Several of the smaller mirrors in the telescope, the tertiary mirror and the fine steering mirror, were coated in 2010. The secondary mirror was finished earlier this year.

Quantum Coating Inc. (QCI) is under contract to Ball Aerospace and Northrop Grumman. QCI constructed a new coating facility and clean room to coat the large mirror segments. QCI developed the gold coating for performance in certain areas, such as uniformity, cryogenic cycling, durability, stress and reflectance, in a two-year effort prior to coating the first flight mirror.

In the process, gold is heated to its liquid point, more than 2,500 Fahrenheit (1,371 degrees Celsius), and evaporates onto the mirror's optical surface. The coatings are 120 nanometers, a thickness of about a millionth of an inch or 200 times thinner than a human hair.

"We faced many technical challenges on the Webb mirror coating program," said Ian Stevenson, director of coating at Quantum Coating. "One of the most daunting was that all flight hardware runs had to be executed without a single failure."

The mirror segments recently were shipped to Ball Aerospace in Boulder, Colo., where actuators are attached that help move the mirror. From there, the segments travel to the X-ray and Calibration Facility at NASA's Marshall Space Flight Center in Huntsville, Ala., to undergo a final test when they will be chilled to -400 Fahrenheit (-240 degrees Celsius). The last batch of six flight mirrors should complete the test by the end of this year.

Robert Pearlman

NASA release

Tests Under Way On The Sunshield For NASA's Webb Telescope

NASA is testing an element of the sunshield that will protect the James Webb Space Telescope's mirrors and instruments during its mission to observe the most distant objects in the universe.

The sunshield will consist of five tennis court-sized layers to allow the Webb telescope to cool to its cryogenic operating temperature of minus 387.7 degrees Fahrenheit (40 Kelvin).

Credit: NASA/Northrop Grumman

Above: The five-layer James Webb Space Telescope sunshield consists of thin membranes made from a polymer-based film and supporting equipment such as spreader bars, booms, cabling, and containment shells.

Testing began early this month at ManTech International Corp.'s Nexolve facility in Huntsville, Ala., using flight-like material for the sunshield, a full-scale test frame and hardware attachments. The test sunshield layer is made of Kapton, a very thin, high-performance plastic with a reflective metallic coating, similar to a Mylar balloon. Each sunshield layer is less than half the thickness of a sheet of paper. It is stitched together like a quilt from more than 52 individual pieces because manufacturers do not make Kapton sheets as big as a tennis court.

The tests are expected to be completed in two weeks.

"The conclusion of testing on this full size layer will be the final step of the sunshield's development program and provides the confidence and experience to manufacture the five flight layers," said Keith Parrish, Webb Sunshield manager at NASA's Goddard Space Flight Center in Greenbelt, Md.

During testing, engineers use a high-precision laser radar to measure the layer every few inches at room temperature and pressure, creating a 3D map of the material surface, which is curved in multiple directions. The map will be compared to computer models to see if the material behaved as predicted, and whether critical clearances with adjacent hardware are achieved.

The test will be done on all five layers to give engineers a precise idea of how the entire sunshield will behave once in orbit. Last year, a one-third-scale model of the sunshield was tested in a chamber that simulated the extreme temperatures it will experience in space. The test confirmed the sunshield will allow the telescope to cool to its operating temperature.

After the full-size sunshield layers complete testing and model analysis, they will be sent to Northrop Grumman in Redondo Beach Calif., where engineers verify the process of how the layers will unfurl in space. There the sunshield layers will be folded, much like a parachute, so they can be safely stowed for launch.

Robert Pearlman

NASA release

NASA's Webb Telescope Flight Backplane Section Completed

The center section of the backplane structure that will fly on NASA's James Webb Space Telescope has been completed, marking an important milestone in the telescope's hardware development. The backplane will support the telescope's beryllium mirrors, instruments, thermal control systems and other hardware throughout its mission.

Credit: NASA/ATK

Above: The center section of the James Webb Space Telescope flight backplane, or Primary Mirror Backplane Support Structure, at ATK's manufacturing facility in Magna, Utah.

"Completing the center section of the backplane is an important step in completing the sophisticated telescope structure," said Lee Feinberg, optical telescope element manager for the Webb telescope at NASA's Goddard Space Flight Center in Greenbelt, Md. "This fabrication success is the result of innovative engineering dating back to the technology demonstration phase of the program."

The center section, or primary mirror backplane support structure, will hold Webb's 18-segment, 21-foot-diameter primary mirror nearly motionless while the telescope peers into deep space. The center section is the first of the three sections of the backplane to be completed.

Measuring approximately 24 by 12 feet yet weighing only 500 pounds, the center section of the backplane meets unprecedented thermal stability requirements. The backplane holds the alignment of the telescope's optics through the rigors of launch and over a wide range of operating temperatures, which reach as cold as - 406 degrees Fahrenheit. During science operations, the backplane precisely keeps the 18 primary mirror segments in place, permitting the mirrors to form a single, pristine shape needed to take sharp images.

Robert Pearlman

NASA release

First flight instrument delivered for James Webb Space Telescope

The first of four instruments to fly aboard NASA's James Webb Space Telescope (Webb) has been delivered to NASA. The Mid-Infrared Instrument (MIRI) will allow scientists to study cold and distant objects in greater detail than ever before.

MIRI arrived at NASA's Goddard Space Flight Center in Greenbelt, Md., on May 29. It has been undergoing inspection before being integrated into Webb’s science instrument payload known as the Integrated Science Instrument Module (ISIM).

Assembled at and shipped from the Science and Technology Facilities Council's Rutherford Appleton Laboratory in the United Kingdom, MIRI was developed by a consortium of 10 European institutions and NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., after having been handed over to the European Space Agency.

MIRI will observe light with wavelengths in the mid-infrared range of 5 microns to 28 microns, which is a longer wavelength than human eyes can detect. It is the only instrument of the four with this particular ability to observe the physical processes occurring in the cosmos.

"MIRI will enable Webb to distinguish the oldest galaxies from more evolved objects that have undergone several cycles of star birth and death," said Matt Greenhouse, ISIM project scientist at Goddard. "MIRI also will provide a unique window into the birth places of stars which are typically enshrouded by dust that shorter wavelength light cannot penetrate."

MIRI's sensitive detectors will allow it to observe light, cool stars in very distant galaxies; unveil newly forming stars within our Milky Way; find signatures of the formation of planets around stars other than our own; and take imagery and spectroscopy of planets, comets and the outermost bits of debris in our solar system. MIRI's images will enable scientists to study an object’s shape and structure.

Robert Pearlman

NASA release (Jan. 24, 2014)

James Webb Space Telescope Passes a Mission Milestone

NASA's James Webb Space Telescope has passed its first significant mission milestone for 2014 — a Spacecraft Critical Design Review (SCDR) that examined the telescope's power, communications and pointing control systems.

"This is the last major element-level critical design review of the program," said Richard Lynch, NASA Spacecraft Bus Manager for the James Webb Space Telescope at NASA's Goddard Space Flight Center in Greenbelt, Md. "What that means is all of the designs are complete for the Webb and there are no major designs left to do."

During the SCDR, the details, designs, construction and testing plans, and the spacecraft's operating procedures were subjected to rigorous review by an independent panel of experts. The week-long review involved extensive discussions on all aspects of the spacecraft to ensure the plans to finish construction would result in a vehicle that enables the powerful telescope and science instruments to deliver their unique and invaluable views of the universe.

"While the spacecraft that carries the science payload for Webb may not be as glamorous as the telescope, it's the heart that enables the whole mission," said Eric Smith, acting program director and program scientist for the Webb Telescope at NASA Headquarters in Washington. "By providing many services including telescope pointing and communication with Earth, the spacecraft is our high tech infrastructure empowering scientific discovery."

"Our Northrop Grumman team has worked exceptionally hard to meet this critical milestone on an accelerated schedule, following the replan," said Scott Willoughby, Northrop Grumman vice president and James Webb Space Telescope program manager in Redondo Beach, Calif. "This is a huge step forward in our progress toward completion of the Webb Telescope."

NASA Administrator Charles Bolden and Senator Barbara Mikulski of Maryland congratulated the James Webb Space Telescope team Monday (Feb. 3) for the delivery of all flight instruments and primary mirrors to NASA's Goddard Space Flight Center in Greenbelt, Md.

Their comments came in a morning news conference at Goddard, where NASA's flagship science project will be assembled in preparation for launch in 2018.

"The Hubble Space Telescope has already rewritten the science books. Going from Hubble to the James Webb Space Telescope is like going from a biplane to the jet engine," said Mikulski, Chairwoman of the Senate Appropriations Committee that funds NASA. "As Chairwoman, I've continued to fight for funds in the federal checkbook to keep the James Webb Space Telescope mission on track, supporting jobs today and jobs tomorrow at Goddard. NASA Goddard is home to leaders in Maryland's space and innovation economies, making discoveries that not only win Nobel Prizes, but create new products and jobs. The James Webb Space Telescope will keep us in the lead for astronomy for decades to come, spurring the innovation and technology that keep America's economy rolling."

NASA's James Webb Space Telescope will be the most powerful space telescope ever built, capable of observing the most distant objects in the universe, providing images of the first galaxies formed, and observing unexplored planets around distant stars. A joint project of NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA), Webb is the successor to the agency's Hubble Space Telescope.

All 18 of Webb's primary mirror segments are now housed in the Goddard clean room. Its 1.3 million cubic feet of dust-free space make the clean room one of the world's largest. All four of Webb's science instruments are within feet of the mirrors. The telescope's mirror and instruments will capture images of the universe and break down the spectra of incoming light to analyze the properties of galaxies, stars, and the atmospheres of planets beyond our solar system.

"The recent completion of the critical design review for Webb, and the delivery of all its instruments to Goddard, mark significant progress for this mission," said Bolden. "The design, build, delivery and testing of these components took meticulous planning and action here at Goddard and with teams across the country, as well as with our international partners. It's very exciting to see it all coming together on schedule. And I want to thank our good friend Senator Barbara Mikulski for her support. We wouldn't be here today without her championing of this critical capability for NASA. I know she understands just how important it is to continue to push the boundaries of what we can do in space."

"This past year has been one of significant progress for the Webb telescope," said Goddard Director Chris Scolese during the news conference. "The NASA Goddard team is working tirelessly with our partners to keep the program on track as we develop this newest scientific tool to explore the universe."

The news conference featured a video presentation hosted by Webb's deputy project manager and technical engineer, Paul Geithner, from inside the clean room. He explained how the 18 mirror segments will be coupled to form the massive space telescope's 21-foot-wide main mirror. This work, and the assembly of the rest of the telescope, will begin once the telescope structure arrives at Goddard.

"Each of these instruments has a unique function to collect data about the universe," Geithner said, pointing to four science instruments that will be located inside the heart of the telescope.

One of these instruments, the University of Arizona's Near-Infrared Camera, will be Webb's primary camera and will take images of the first stars and galaxies to form in the universe, along with many other astronomical targets.

A second instrument, ESA's Near-Infrared Spectrograph (NIRSpec), will analyze the spectra and composition of as many as 100 objects at once. Airbus Defence and Space, formerly known as EADS/Astrium, built NIRSpec with components provided by Goddard.

A third instrument, ESA's Mid-Infrared Instrument, has both a camera and a spectrograph, which sees light in the mid-infrared region of the electromagnetic spectrum -- wavelengths longer than the human eye can see. This instrument was developed in collaboration with NASA's Jet Propulsion Laboratory in Pasadena, Calif.

A fourth instrument, CSA's Fine Guidance Sensor and Near-infrared Imager and Slitless Spectrograph, will allow Webb to point precisely at its target in order to obtain high-quality images, and also will provide other valuable science modes for investigating both the distant universe and nearby exoplanets.

Northrop Grumman Aerospace Systems is building Webb's sunshield. Once in space, the sunshield will act as an umbrella to keep heat radiating from the sun and Earth from reaching scientific instruments that must stay cold to function properly. The Webb telescope will be fully assembled by 2016 and then moved to a clean room at NASA's Johnson Space Center for additional testing.

Robert Pearlman

NASA release

Testing Completed on NASA's James Webb Space Telescope Backplane

NASA's James Webb Space Telescope has reached another development milestone with the completion of static load testing of its primary mirror backplane support structure (PMBSS) moving the telescope one step closer to its 2018 launch.

The PMBSS is the stable platform that holds the telescope's science instruments and the 18 beryllium mirror-segments that form the 21-foot-diameter primary mirror nearly motionless while the telescope peers into deep space. The primary mirror is the largest mirror in the telescope -- the one starlight will hit first.

Above: The backplane of NASA’s James Webb Space Telescope was mounted to a structure for static load testing to verify it can withstand the rigors of launch and hold the weight needed to support the telescope in space. Credit: Northrop Grumman

"Static testing demonstrates the backplane has the structural integrity to withstand the forces and vibrations of launch and is the final test prior to starting the integration of the backplane with the rest of the telescope," said Lee Feinberg, NASA’s Optical Telescope Element manager at the agency’s Goddard Space Flight Center in Greenbelt, Maryland.

The Northrop Grumman Corporation and ATK of Magna, Utah, completed the testing before delivering the structure to Northrop Grumman's facilities in Redondo Beach, California.

"This is the largest, most complex cryogenically stable structure humans have ever built," said Scott Texter, Optical Telescope Element manager for Northrop Grumman. "Completion of the static testing verifies it can hold the weight it is designed to hold. Now the structural backbone of the observatory is officially verified and ready for integration."

Despite its size and complexity, the PMBSS is one of the most lightweight precision-alignment truss structures ever designed and built. When fully deployed, it measures approximately 24 feet tall by 19.5 feet wide by more than 11.5 feet deep, and weighs only 2,180 pounds. Once fully assembled and populated, the PMBSS will support a mission payload and instruments that weigh more than 7,300 pounds. With a full launch load, it will support the equivalent of 12 times its own weight.

The PMBSS is designed to minimize changes in the shape of the telescope caused when one side is hotter than the other. While the telescope is operating at a range of extremely cold temperatures, between -406 and -343 degrees Fahrenheit, the backplane must not move more than 38 nanometers, approximately 1/1,000 the diameter of a human hair.

Under contract from NASA, Northrop Grumman is the lead contractor for the design and development of the Webb telescope's optics, sunshield and spacecraft. ATK designed, engineered and constructed more than 10,000 parts for the PMBSS at its facilities in Magna. They used composite parts, lightweight graphite materials, state-of-the-art material sciences and advanced fabrication techniques to build the structure.

The next step for the space telescope is to integrate the composite structures with the deployment mechanisms to create the overall Optical Telescope Element (OTE) structure. The OTE structure will then be shipped to Goddard for integration with the mirrors. NASA and Northrop Grumman will perform cryogenic testing of the PMBSS structure after mirror integration is complete.

Robert Pearlman

NASA photo release

NASA's Webb Sunshield Stacks Up to Test

The Sunshield on NASA's James Webb Space Telescope is the largest part of the observatory—five layers of thin membrane that must unfurl reliably in space to precise tolerances. Last week, for the first time, engineers stacked and unfurled a full-sized test unit of the Sunshield and it worked perfectly.

The Sunshield is about the length of a tennis court, and will be folded up like an umbrella around the Webb telescope’s mirrors and instruments during launch. Once it reaches its orbit, the Webb telescope will receive a command from Earth to unfold, and separate the Sunshield's five layers into their precisely stacked arrangement with its kite-like shape.

The Sunshield test unit was stacked and expanded at a cleanroom in the Northrop Grumman facility in Redondo Beach, California.

The Sunshield separates the observatory into a warm sun-facing side and a cold side where the sunshine is blocked from interfering with the sensitive infrared instruments. The infrared instruments need to be kept very cold (under 50 K or -370 degrees F) to operate. The Sunshield protects these sensitive instruments with an effective sun protection factor or SPF of 1,000,000 (suntan lotion generally has an SPF of 8-50).

In addition to providing a cold environment, the Sunshield provides a thermally stable environment. This stability is essential to maintaining proper alignment of the primary mirror segments as the telescope changes its orientation to the sun.

Robert Pearlman

NASA release

Building Hubble's Successor: Crucial Pathfinder Test Set Up Inside Chamber A

Inside NASA's giant thermal vacuum chamber, called Chamber A, at NASA's Johnson Space Center in Houston, the James Webb Space Telescope's Pathfinder backplane test model, is being prepared for its cryogenic test. Previously used for manned spaceflight missions, this historic chamber is now filled with engineers and technicians preparing for a crucial test.

Exelis developed and installed the optical test equipment in the chamber.

"The optical test equipment was developed and installed in the chamber by Exelis," said Thomas Scorse, Exelis JWST Program Manager. "The Pathfinder telescope gives us our first opportunity for an end-to-end checkout of our equipment."

"This will be the first time on the program that we will be aligning two primary mirror segments together," said Lee Feinberg, NASA Optical Telescope Element Manager. "In the past, we have always tested one mirror at a time but this time we will use a single test system and align both mirrors to it as though they are a single monolithic mirror."

Robert Pearlman

NASA release

NASA's Webb Space Telescope Receives First Mirror Installation

NASA has successfully installed the first of 18 flight mirrors onto the James Webb Space Telescope, beginning a critical piece of the observatory's construction.

In the clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland this week, the engineering team used a robot arm to lift and lower the hexagonal-shaped segment that measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms). After being pieced together, the 18 primary mirror segments will work together as one large 21.3-foot (6.5-meter) mirror. The full installation is expected to be complete early next year.

"The James Webb Space Telescope will be the premier astronomical observatory of the next decade," said John Grunsfeld, astronaut and associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. "This first-mirror installation milestone symbolizes all the new and specialized technology that was developed to enable the observatory to study the first stars and galaxies, examine the formation stellar systems and planetary formation, provide answers to the evolution of our own solar system, and make the next big steps in the search for life beyond Earth on exoplanets."

Several innovative technologies have been developed for the Webb Telescope, which is targeted for launch in 2018, and is the successor to NASA's Hubble Space Telescope. Webb will study every phase in the history of our universe, including the cosmos' first luminous glows, the formation of solar systems capable of supporting life on planets like Earth, and the evolution of our own solar system.

The 18 separate segments unfold and adjust to shape after launch. The mirrors are made of ultra-lightweight beryllium chosen for its thermal and mechanical properties at cryogenic temperatures. Each segment also has a thin gold coating chosen for its ability to reflect infrared light. The telescope's biggest feature is a tennis court sized five-layer sunshield that attenuates heat from the sun more than a million times.

"After a tremendous amount of work by an incredibly dedicated team across the country, it is very exciting to start the primary mirror segment installation process" said Lee Feinberg, James Webb Space Telescope optical telescope element manager at Goddard. "This starts the final assembly phase of the telescope."

The mirrors must remain precisely aligned in space in order for Webb to successfully carry out science investigations. While operating at extraordinarily cold temperatures between minus 406 and minus 343 degrees Fahrenheit, the backplane must not move more than 38 nanometers, approximately one thousandth the diameter of a human hair.

"There have many significant achievements for Webb over the past year, but the installation of the first flight mirror is special," said Bill Ochs, James Webb Space Telescope project manager. "This installation not only represents another step towards the magnificent discoveries to come from Webb, but also the culmination of many years of effort by an outstanding dedicated team of engineers and scientists."

The mirrors were built by Ball Aerospace & Technologies Corp., Boulder, Colorado. Ball is the principal subcontractor to Northrop Grumman for the optical technology and lightweight mirror system.

The James Webb Space Telescope is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency. NASA works with the international science community to explore our solar system and beyond. We look to unravel mysteries that intrigue us all as we explore to answer big questions, like how did our solar system originate and change over time, and how did the universe begin and evolve, and what will be its destiny?

The 18th and final primary mirror segment is installed on what will be the biggest and most powerful space telescope ever launched. The final mirror installation Wednesday at NASA's Goddard Space Flight Center in Greenbelt, Maryland marks an important milestone in the assembly of the agency's James Webb Space Telescope.

Above: Inside a massive clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland the James Webb Space Telescope team used a robotic am to install the last of the telescope's 18 mirrors onto the telescope structure. Credit: NASA/Chris Gunn

"Scientists and engineers have been working tirelessly to install these incredible, nearly perfect mirrors that will focus light from previously hidden realms of planetary atmospheres, star forming regions and the very beginnings of the Universe," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate in Washington. "With the mirrors finally complete, we are one step closer to the audacious observations that will unravel the mysteries of the Universe."

Using a robotic arm reminiscent of a claw machine, the team meticulously installed all of Webb's primary mirror segments onto the telescope structure. Each of the hexagonal-shaped mirror segments measures just over 4.2 feet (1.3 meters) across -- about the size of a coffee table -- and weighs approximately 88 pounds (40 kilograms). Once in space and fully deployed, the 18 primary mirror segments will work together as one large 21.3-foot diameter (6.5-meter) mirror.

"Completing the assembly of the primary mirror is a very significant milestone and the culmination of over a decade of design, manufacturing, testing and now assembly of the primary mirror system," said Lee Feinberg, optical telescope element manager at Goddard. "There is a huge team across the country who contributed to this achievement."

While the primary mirror installation may be finished on the tennis court-sized infrared observatory, there still is much work to be done.

Above: In this rare view, the James Webb Space Telescope's 18 mirrors are seen fully installed on the James Webb Space Telescope structure at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Credit: NASA/Chris Gunn

"Now that the mirror is complete, we look forward to installing the other optics and conducting tests on all the components to make sure the telescope can withstand a rocket launch," said Bill Ochs, James Webb Space Telescope project manager. "This is a great way to start 2016!"

The mirrors were built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. Ball is the principal subcontractor to Northrop Grumman for the optical technology and optical system design. The installation of the mirrors onto the telescope structure is performed by Harris Corporation, a subcontractor to Northrop Grumman. Harris Corporation leads integration and testing for the telescope.

"The Harris team will be installing the aft optics assembly and the secondary mirror in order to finish the actual telescope," said Gary Matthews, director of Universe Exploration at Harris Corporation. "The heart of the telescope, the Integrated Science Instrument Module, will then be integrated into the telescope. After acoustic, vibration, and other tests at Goddard, we will ship the system down to Johnson Space Center in Houston for an intensive cryogenic optical test to ensure everything is working properly."

Robert Pearlman

NASA release

James Webb Space Telescope's Golden Mirror Unveiled

NASA engineers recently unveiled the giant golden mirror of NASA's James Webb Space Telescope as part of the integration and testing of the infrared telescope.

The 18 mirrors that make up the primary mirror were individually protected with a black covers when they were assembled on the telescope structure. Now, for the first time since the primary mirror was completed, the covers have been lifted.

Standing tall and glimmering gold inside NASA's Goddard Space Flight Center's clean room in Greenbelt, Maryland, this mirror will be the largest yet sent into space. Currently, engineers are busy assembling and testing the other pieces of the telescope.

Scientists from around the world will use this unique observatory to capture images and spectra of not only the first galaxies to appear in the early universe over 13.5 billion years ago, but also the full range of astronomical sources such as star forming nebulae, exoplanets, and even moons and planets within our own Solar System. To ensure the mirror is both strong and light, the team made the mirrors out of beryllium. Each mirror segment is about the size of a coffee table and weighs approximately 20 kilograms (46 pounds). A very fine film of vaporized gold coats each segment to improve the mirror's reflection of infrared light. The fully assembled mirror is larger than any rocket so the two sides of it fold up. Behind each mirror are several motors so that the team can focus the telescope out in space.

This widely anticipated telescope will soon go through many rigorous tests to ensure it survives its launch into space. In the next few months, engineers will install other key elements, and take additional measurements to ensure the telescope is ready for space.

Robert Pearlman

NASA release

NASA Completes Webb Telescope Center of Curvature Pre-test

Engineers and technicians working on the James Webb Space Telescope successfully completed the first important optical measurement of Webb's fully assembled primary mirror, called a Center of Curvature test.

Taking a "before" optical measurement of the telescope's deployed mirror is crucial before the telescope goes into several stages of rigorous mechanical testing. These tests will simulate the violent sound and vibration environments the telescope will experience inside its rocket on its way out into space. This environment is one of the most stressful structurally and could alter the shape and alignment of Webb's primary mirror, which could degrade or, in the worst case, ruin its performance.

Webb has been designed and constructed to withstand its launch environment, but it must be tested to verify that it will indeed survive and not change in any unexpected way. Making the same optical measurements both before and after simulated launch environment testing and comparing the results is fundamental to Webb's development, assuring that it will work in space.

"This is the only test of the entire mirror where we can use the same equipment during a before and after test," said Ritva Keski-Kuha, the test lead and NASA's Deputy Telescope Manager for Webb at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "This test will show if there are any changes or damages to the optical system."

In order to conduct the test, optical engineers set up an interferometer, the main device used to measure the shape of Webb's mirror. Waves of visible light are less than a thousandth of a millimeter long, and optics like Webb's need to be shaped and aligned even more accurately than this to work correctly. Making measurements of the mirror shape and position by lasers prevents physical contact and damage (scratches to the mirror). So scientists use wavelengths of light to make tiny measurements. By measuring light reflected off the optics using an interferometer, they are able to measure extremely small changes in shape or position. An interferometer gets its name from the process of recording and measuring the ripple patterns that result when different beams of light mix and their waves combine or 'interfere.'

During the test conducted by a team from NASA Goddard, Ball Aerospace of Boulder, Colorado, and the Space Telescope Science Institute in Baltimore Maryland, temperature and humidity conditions in the cleanroom were kept incredibly stable to minimize drift in the sensitive optical measurements over time. Even so, tiny vibrations are ever-present in the cleanroom that cause jitter during measurements, so the interferometer is a 'high-speed' one, taking 5,000 'frames' every second, which is a faster rate than the background vibrations themselves. This allows engineers to subtract out jitter and get good, clean results.

The Center of Curvature test measures the shape of Webb's main mirror by comparing light reflected off of it with light from a computer-generated hologram that represents what Webb's mirror ideally should be. By interfering the beam of light from Webb with the beam from the hologram reference, the interferometer accurately compares the two by measuring the difference to incredible precision. "Interferometry using a computer-generated hologram is a classic modern optical test used to measure mirrors," said Keski-Kuha.

With the largest mirror of any space telescope, taking this measurement is a challenge. "We have spent the last four years preparing for this test," said David Chaney, Webb's primary mirror metrology lead at Goddard. "The challenges of this test include the large size of the primary mirror, the long radius of curvature, and the background noise. Our test is so sensitive we can measure the vibrations of the mirrors due to people talking in the room."

After the measurements come back from the interferometer the team will analyze the data to make sure the mirrors are aligned perfectly before the launch environment tests. The Center of Curvature test will be repeated after the launch environment testing and the results compared to confirm that Webb's optics will work after their launch into space.

The most powerful space telescope ever built, the Webb telescope will provide images of the first galaxies ever formed, and explore planets around distant stars. It is a joint project of NASA, the European Space Agency and the Canadian Space Agency.